Got Shell 93 Octane and now barely idles 1973 Dart 340
Take the carb off and get a clean bowl and turn the carb upside down and shake it until it's emptied all the gas in the bowl,it'll come out thru the air horn.
You see water? If not it's not water and more than likely a vacuum leak. Always a possibility a small piece of grit made it to a idle passage.
Don't forget to remove the fuel filter and empty it into a bowl and look for water or trash.